INORGANIC ANDORGANOMETALLICPOLYMERS

RONALD D. ARCHERProfessor EmeritusUniversity of Massachusetts, Amherst

A John Wiley & Sons, Inc., Publication

New York Chichester Weinheim Brisbane Singapore Toronto

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INORGANIC ANDORGANOMETALLICPOLYMERS

Special Topics in Inorganic Chemistry

Series Editor

R. Bruce KingDepartment of ChemistryUniversity of Georgia

Books in the Series

Brian N. Figgis and Michael A. HitchmanLigand Field Theory and Its Applications

INORGANIC ANDORGANOMETALLICPOLYMERS

RONALD D. ARCHERProfessor EmeritusUniversity of Massachusetts, Amherst

A John Wiley & Sons, Inc., Publication

New York Chichester Weinheim Brisbane Singapore Toronto

Designations used by companies to distinguish their products are often claimed as trademarks. Inall instances where John Wiley & Sons, Inc., is aware of a claim, the product names appear ininitial capital or ALL CAPITAL LETTERS. Readers, however, should contact the appropriatecompanies for more complete information regarding trademarks and registration.

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Archer, Ronald D.Inorganic and organometallic polymers / Ronald D. Archer.

p. cm (Special topics in inorganic chemistry)Includes bibliographical references and index.ISBN 0-471-24187-3 (cloth : alk. paper)1. Inorganic polymers. 2. Organometallic polymers. I. Title. II. Series.

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SPECIAL TOPICS IN INORGANICCHEMISTRY

This text represents the second in a series of one-volume introductions tomajor areas of inorganic chemistry written by leaders in the field. Inorganicchemistry covers a variety of diverse substances including molecular, coordina-tion, organometallic, and nonmolecular compounds as well as special materialssuch as metallobiomolecules, semiconductors, ceramics, and minerals. The greatstructural diversity of inorganic compounds makes them vitally important asindustrial feedstocks, fine chemicals, catalysts, and advanced materials. Inorganiccompounds such as metalloenzymes also play a key role in life processes. Thisseries will provide valuable, concise graduate texts for use in survey coursescovering diverse areas of inorganic chemistry.

R. Bruce King, Series EditorDepartment of Chemistry

University of GeorgiaAthens, Georgia USA

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CONTENTS

Preface xi

1 INORGANIC POLYMERS AND CLASSIFICATION SCHEMES 1

1.1 Introduction 11.1.1 What Is an Inorganic Polymer? 2

1.2 Classifications by Connectivities 31.2.1 Connectivities of 1 31.2.2 Connectivities of 2 51.2.3 Connectivities of 3 61.2.4 Mixed Connectivities of 2 and 3 81.2.5 Connectivities of 4 91.2.6 Mixed Connectivities of 3 and 4 91.2.7 Connectivities of 6 91.2.8 Mixed Connectivities of 4 and 6 111.2.9 Connectivities of 8 12

1.3 Classifications by Dimensionality 121.3.1 1-D Polymeric Structures 121.3.2 2-D Polymeric Structures 131.3.3 3-D Polymeric Structures 15

1.4 The Metal/Backbone Classification of Metal-ContainingPolymers 161.4.1 Type I Metal-Backbone Polymers 171.4.2 Type II Metal-Enmeshed Polymers 18

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1.4.3 Type III Anchored Metal Polymers 191.5 Linear Inorganic Polymers The Thrust of this Book 20

1.5.1 Metal-Containing Polymers 201.5.2 Main Group Inorganic Polymers 25

References 31Exercises 32

2 INORGANIC POLYMER SYNTHESES 35

2.1 Step-Growth Syntheses 352.1.1 Step Condensation Synthesis Generalities 362.1.2 Step Condensation Syntheses of Metal-Containing

Polymers 402.1.3 Main Group Step Condensation Polymer Syntheses 522.1.4 Step Addition Syntheses 57

2.2 Chain Polymerizations 582.2.1 Radical Polymerizations 602.2.2 Cationic Polymerizations 652.2.3 Anionic Polymerizations 68

2.3 Ring-Opening Polymerizations 692.3.1 Metal-Coordination ROP 702.3.2 Organometallic ROP 702.3.3 Main Group ROP 73

2.4 Reductive Coupling and Other Redox Polymerization Reactions 782.4.1 Reductive Coupling 782.4.2 Oxidative Addition Polymerizations 80

2.5 Condensation (Desolvation) Oligomerizations/Polymerizations 812.5.1 Cationic Aggregations 822.5.2 Anionic Aggregations 822.5.3 Desolvation at Elevated Temperature 832.5.4 Solvolysis-Desolvation Reactions 83

2.6 Miscellaneous Synthesis Comments 842.6.1 Solubility 842.6.2 Telechelic Polymers 872.6.3 Catalyzed Dehydrogenation Reactions 87

References 87Exercises 91

3 INORGANIC POLYMER CHARACTERIZATION 93

3.1 Average Molecular Masses and Degrees of Polymerization 94

CONTENTS ix

3.2 Methods of Characterizing Average Molecular Masses 993.2.1 Gel Permeation Chromatography 993.2.2 Viscosity 1033.2.3 Universal Calibration 1103.2.4 Light Scattering for Absolute Molecular Mass and

Size Measurements 1143.2.5 Colligative Properties (Vapor Pressure Lowering, Boiling

Point Elevation, Melting Point Lowering, and OsmoticPressure) 116

3.2.6 End-Group Analyses 1193.2.7 Mass Spectroscopy 1243.2.8 Ultracentrifugation 124

3.3 Determinations of Thermal Parameters 1263.3.1 Glass Transition Temperature Measurements 1273.3.2 Other Thermal Parameters 132

3.4 Spectroscopic Characterizations Specific to Inorganic Polymers 1333.4.1 Nuclear Magnetic Resonance Spectroscopy 1333.4.2 Electron Paramagnetic Resonance Spectroscopy 1363.4.3 Electronic Spectroscopies 1423.4.4 Vibrational Spectroscopies 1523.4.5 Mossbauer Spectroscopy 1583.4.6 Other Spectroscopic Methods 165

3.5 Viscoelasticity Measurements 1673.6 Crystallization Characterization 170

3.6.1 Birefringent Microscopy 1713.6.2 Wide-Angle X-Ray Scattering 1713.6.3 Small-Angle X-Ray Scattering 1723.6.4 Small-Angle Polarized Light Scattering 1723.6.5 Electron Scattering 1723.6.6 Neutron Scattering 173

3.7 Concluding Statement 173References 173Exercises 177

4 PRACTICAL INORGANIC POLYMER CHEMISTRY 179

4.1 Inorganic Polymer Elastomers 1794.1.1 Polysiloxane Elastomers 1804.1.2 Polyphosphazene Elastomers 1824.1.3 Other Inorganic Elastomers 186

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4.2 Interface Coupling Reactions 1864.2.1 Silicon Coupling Agents 1864.2.2 Metal Coupling Agents 188

4.3 Inorganic Dental Polymers and Adhesives 1934.4 Inorganic Medical Polymers 194

4.4.1 Polysiloxanes as Biopolymers 1944.4.2 Polyphosphazenes as Biopolymers 1974.4.3 Metal-Containing Polymers for Medical Purposes 198

4.5 Inorganic High-Temperature Fluids and Lubricants 1984.6 Inorganic Polymers as Lithographic Resists 2024.7 Inorganic Polymers as Preceramics 207

4.7.1 Silicon Carbide from Polycarbosilanes 2074.7.2 Silicon Nitride Preceramic Polymers 2094.7.3 Other Preceramic Polymers 210

4.8 Inorganic Polymer Conductivity 2124.8.1 Main Group Inorganic Polymers 2124.8.2 Metal-Containing Polymers 214

4.9 Nonlinear Optics Metal-Containing Polymers 2174.10 Luminescent Inorganic Polymers 218

4.10.1 Ruthenium Polymers for Solar Energy Conversion 2184.10.2 Other Luminescent Metal Polymers 2214.10.3 Silicon Luminescent Materials 221

4.11 Magnetic Metal-Coordination Polymers 2224.12 Inorganic Polymers as Catalysts 2254.13 Miscellaneous Uses 226References 226Exercises 232

Epilogue 235

Index 237

PREFACE

If I were to have a special dedication, it would be to the late John C. Bailar, Jr.,my Ph.D. mentor. John piqued my interest in the stereochemistry of monomericcoordination compounds initially, and his statement regarding the apparentimpossibility of preparing soluble metal coordination polymers of high molecularmass became a challenge that twenty years later put me on the quest for thesoluble eight-coordinate polymers. You will find the successful results sprinkledthroughout this book.

A number of books and textbooks on inorganic materials chemistry exist. Theonly recent textbook on inorganic polymers is very heavily weighted towardmain group polymers. Recent advances in metal-containing polymers led me todevelop a special-topics graduate course on inorganic polymers. The success ofthis course led Prof. R. Bruce King, the series editor, to suggest that I write aninorganic polymer book suitable for graduate students. It has been a joy to writethe book because so much is happening in the field and I have learned so muchmore myself.

I thank profusely the research students, postdoctoral associates, visitingscientists, and co-investigators with whom I worked on inorganic polymersand who provided the incentive for producing this text. This includes severalshort-term undergraduate exchange students from Germany and Britain whomade significant research contributions, too. Also, special thanks to the graduatestudents who took the special-topics graduate course on inorganic polymers andprovided valuable input to the manuscript. Thanks also to the University ofMassachusetts Polymer Science and Engineering Department and Department ofChemistry colleagues who have aided my knowledge in polymer science andhave allowed my group to use their equipment.

Prepublication materials from Leonard Interrante and Charles Carraher aremost graciously appreciated. I wish to acknowledge the help received from

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xii PREFACE

the extensive reviews by Harry Allcock, (especially his and F. W. LampesContemporary Polymer Chemistry textbook published by Prentice-Hall in 1981and 1990), Charles Carraher, Ian Manners, Charles Pittman, Jan Rehahn, andmany others you will find referenced in the text.

The staff at John Wiley have been most helpful, and I especially want tothank Darla Henderson, Danielle Lacourciere, and Amy Romano, all of whomhave shown me an extraordinary amount of patience.

Finally, ardent thanks and appreciation to Joyce, my devoted wife since 1954,for all of the sacrifices she has endured to make my career and this book a reality.Without her support, this book could not have been completed.

Ronald D. ArcherAmherst, Massachusetts

CHAPTER 1

INORGANIC POLYMERS ANDCLASSIFICATION SCHEMES

1.1 INTRODUCTION

This is an exciting time to be involved in the field of inorganic polymers.The advances being made in the core areas of inorganic polymer chemistry aretruly remarkable and outstanding, using any logical definition. Recent syntheticbreakthroughs are very impressive. Just a few years ago, no one envisionedthe synthesis of polyphosphazenes at room temperature or the ready synthesis oforganometallic polymers through ring-opening polymerizations. Both are realitiesat the present time. These and other examples of both main group and metal-containing polymers are discussed in Chapter 2.

Uses for inorganic polymers abound, with advances being made continually.Polysiloxane and polyphosphazene elastomers, siloxane and metal-containingcoupling agents, inorganic dental polymers, inorganic biomedical polymers,high temperature lubricants, and preceramic polymers are examples of majorapplications for inorganic polymers. Conducting and superconducting inor-ganic polymers have been investigated as have polymers for solar energyconversion, nonlinear optics, and paramagnets. These uses are detailed inChapter 4. If we were to include inorganic coordination and organometallicspecies anchored to organic polymers and zeolites, catalysis would also be amajor use.

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